1. Field of the Invention
The present invention relates to a semiconductor device manufacturing apparatus and, more particularly, to an apparatus for stacking a plurality of semiconductor chips having the same or similar size.
2. Description of the Related Art
A chip bonding process is generally a process for attaching a semiconductor chip to a substrate such as a lead frame or a printed circuit board. Conventionally, an adhesive means used in the chip bonding process comprises a conductive liquid adhesive such as Ag-epoxy, Ag-glass or solder, or an insulating liquid adhesive such as epoxy or silicone. A predetermined amount of the liquid adhesive is applied on the substrate. The semiconductor chip is placed on and pressed down on the liquid adhesive.
The conventional die bonding method using such liquid adhesive has several disadvantages. For example, it is difficult to control the thickness of the liquid adhesive. If a thin semiconductor chip, e.g. having a thickness of 180 μm or less, is used, voids may be generated in the liquid adhesive due to the warpage of the semiconductor chip. Such voids may reduce the reliability of the semiconductor device. Also, if the semiconductor chips are stacked in a three-dimensional arrangement, the rolling defect of the liquid adhesive may make the stacking of semiconductor chips having the same or similar size difficult.